Gearing



H. F. SCHMIDT.

GEARING.

APPLICATION FILED APR. 24, 1918.

a 1 3 97 PatentedAug. 30, 1921.

'IIIIIIIIIIIII 9 I I /0 v W ATTORNEY}.

UNITEDSTATES HENRY IE. SCHMIDT, or wrnxmsnune, PENNSYLVANIA, ASSIGNOR 'rownsrmm J I PATENT OFFICE;

HOUSE GEAR & DYNAMOMETER COMPANY, A CORPORATION 013 PENNSYL- VANIA.

GEARING;

To all whom it mag concern: c

Be it knownthat I, HENRY F. SCHMIDT, a citizen of the United States, and a resident of Wilkinsburg, in the county of Allegheny and State of Pennsylvania, have made a new and useful Invention in Gearing, 1 of which the following is a specification.

i This invention relates to gearing and particularly to reduction gearing capable of transm'ittinglarge power.

An objectof the invention is to'produce a new and improved gearing in which the tor.- sional deflection of the pinion or smaller gear varies at a uniform rate throughout the length of the gear.

A further object is to produce a new and improved gear or pinion which is so formed as to insure uniform loading of the gear teeth when the gear or pinion is transmitting power and is consequently subjected to torsional deflecting strains.

A further object is to produce a pinion or gear which is so formed that its moment of inertia varies at different points along its length so as to produce a constant deflection per unit of length'when the gear is subjected to torsionalor twisting strains.

These and other objects are attained by means of a features here n described and illustrated in the drawings accompanying and forming a part hereof. s

Driving pinions of reduction'gearing are ordinarily of relatively small diameter and particularly when compared to the driven gear with which they mesh. Whensuch pinions are subjected to torsional or twisting strains they deflect, and inasmuch :as the driven gear with which they mesh is usually materially larger and consequently more rigid, some means must be employed for" compensating for the torsionaldeflection of the smaller gearor pinion in order that the tooth pressures may be maintained substantially uniform per unit of'length of the pin ion. The only successful method. of accomplishing this result is to so mountthe pinion that it is capable of moving to difl'erent angular positions relatively to the axis of the driven gear, when it deflects under torsional strains. This angular motion ofthe pinion compensates :for the torsional distortion of its teeth and therefore tends to distribute tooth pressures uniformly across the faces of ear or pinion embodying the.-

I Specification of Letters Patent. Patented Aug. 30, 1921,

Application filed. April 24,

1918. Serial No. 230,450.'

the intermeshing'teeth. Where the pinion is so formed that its moment of inertia, about the axis of the pinion, is uniform throughout the length of the pinion, the torsional"de-- flection varies from oneendof the pinion to the other. This is particularly true when the driving force is transmitted to one end of the pinion, but it is also a well knownfact that it occurs when the teeth .ofrthe pinion are subjected to uniform load per unit of length." In order to overcome the difficulty occasioned by aivariation in the deflection throughoutgthe' length ofrithe gear, I) have so formed the pinion that its moment of inertia, about the axis of the pinion, is Varied from one end of the pinion to the other, in such a way as to produce a uniform or constant deflection per unit of length of the pinion when the pinion is subjected to twisting or torsional strains.

In the drawings tional view of a pinion embodying my invention. As illustrated, the pinion consists of a tubular member 5, on which two sets of teeth 7 and 8 areformed. -The separate sets of teeth may be separated by an interveningspace 9, which, with the ends of the illustrated thepinion so formed that its section is gradually reduced from the driving to the free end of the pinion. This reduction in section is accomplished by tapering the hole which extends through the pinion and occasions a reduction in the moment of inertia about the axis of the pinion from the driving to the free end thereof. The distribution of material throughout the length of the pinion is such that the moment of inertia varies from one end to the other so as to occasion a uniform torsional deflection when the pinion is subjected to torsional or twisting strains. This distribution of metal throughoutthelength of the pinion in effect weakens the free end of the inion so that the deflection at this point is increased over I have illustrateda sec-- that whi h would o cur it the P n were of uniform section from end to end. By a proper proportioning of the distributlon of metal,,I am able to obtain a uniform deflection from one end of the gear to the'otherj porting frame of the pinion will shift the pinion to such an angular position, withrelatlon to the axis of the driven gear, that the tooth pressures throughout the length of the gearwill be maintained absolutely uniform.

,Itwill be obvious to thoseskilled in the art that. my invention is particularly useful in connection with turbo-reduction gear installations. It is common practice to em ploy a floating frame in connection with the pinion member in such an installation and ordinarily the pinion member must have some form of flexible connection with the turbine shaft. Accordingly, I connect my pinion with a flexible shaft so that the pin ion may move angularly in an axial plane to the necessary extent in order to present straight lines of pinion teeth in full contact with the gear teeth. Ordinarily, the journal portions outside of and between the pinion portions 7 and 8 would be carried in the bearings of a floating frame. The necessary flexibility having been-provided between the axis-of the pinion and the axis of the turbine by the means referred to, it then becomes necessary, to so design the pinion portions that the torsional deflection, necessarily present due'to the peculiarities of the structure adopted, is made uniform per unit of length along each pinion portion so that straight lines of contact along the pinion teethwill be preserved. Any change in the helix angle of the teeth will be compensated for by movement of the floating frame.

-lVhile I have described and illustrated but one embodiment of my invention, it will be apparent to those skilled in the art that various modifications, additions, changes,

and omissions may be made in the apparatus illustrated without departing from the spirit and scope of the invention, as set forth by the appended claims. I I

What I claim is 1. A tubular gear having a power connec-' tion portion and another portion adapted to be free of the driving connection and the massof said last portion being so disposed that the moment of inertia; decreases gradually outwardly from the connection, portion whereby the gear may deflect uniformly per unit of length.

moment of inertia about theaxis of the gear portion varies fromone end to the other so to uniform load.

a. A driving pinion for. a transmission, gearing, comprlsmg a tubular member hav-- lng gear teeth on the outer facethereofa'nd as to produce a uniform deflection per unit of length and subjection of the teeth thereof to which the driving force is transmitted to substantially one portion of the pinion,

characterized by the fact that the metal of the pinion is so distributed lengthwise of the pinionthat the moment of inertia about the axis thereof varies from the point ofapplication of the driving force :toWard the free'ends of the gearing so as to produce a uniform deflection per unit of lengthrwhen I the pinion is subjected to torsional orptwist ing strains;

'5. A pinion comprising a tubular member.

adapted for connection at a single end to a power transmitting memberand hav ng two sets of teeth formed on the outer peripheral face thereof and spaced one from the other,

the tubular portions having the teethbeing tapered sozthat saidportions may uniformly per unit of length.

6. A pinion comprising a member having .100 deflect a plurality of sets of gear teeth formed on" the peripheral surface thereof, and having. an axial opening extendingtherethrough, said opening being tapered at points along the length thereof corresponding to the spacing of the sets of gear teeth.

Gearing comprising a hollow cylindrical member provided with teeth-on the outer surface thereof and having a tapered hole extendingtherethrough, and a shaft having a driving connection with the one end of the gear.

' 8. Gearing comprisinga hollow cylindri cal member provi ded with teeth on the outer surface thereof and having a' tapered hole terminating in a power CODHGCtlOItPOItlQIl and a shaft extending through the .hole and having a driving connection with the gear at the power connection portion.

9. In gearing, the combination of a pinion member having'journal and pinion portions and a flexible power transmitting member connected to'thepinion memberat one side I of the pinion portions, the pinion portions 2. A gear comprising a tubular memberhaving varying moments of. inertia from gear at only 10 tion of the pinionmember in an axial plane Witness:

end to end in order to secure uniform deflec and the pinion portions having their respection thereof and preservation of the tooth tive masses so distributed that the torsional lines in operation. deflection in each pinion portion takes place I i 10. In gearing, the combination of a pinuniformly and the teeth thereofpreserve'is 5 ion member having a plurality of pinion their lines of contact. I I portions and journal portions outside of and In testimony whereof, I have hereunto 7 between the pinion portions and a flexible: subscribed my name this 22nd day of April,

power transmitting member connected to 1918. the pinion member so as to allow of deflec- HENRY F. SCHMIDT, v

relative to the power transmitting member C. W. MoGHEE. 

